Recent advances in fabricating 3D micro- and nanostructures using carbon microelectromechanical systems, or C-MEMS, has opened up a wide variety of new and exciting applications. The development of 3D C-MEMS has been catapulted forward by the use of transparent, high-viscosity resists such as SU-8. The electrical characteristics and shrinkage of various thickness carbon films derived from SU-8 and AZ P4620 are quantified and discussed in the context of the decomposition and carbonization mechanisms of epoxy and phenolic resins. Measurements obtained reveal a thickness dependence of the resistivity at lower carbonization temperatures but not much dependence at 1000 degrees C. Possible explanations for this low-temperature thickness dependence are given. The electrical characteristics of carbon films obtained from both types of photoresists carbonized at 1000 degrees C are very similar to that of glassy carbon. Simulations have been carried out to demonstrate the importance of the carbon resistivity for C-MEMS devices when used in conductive media. A method for simple optimization and verification of C-MEMS device designs for use in conductive media is introduced. (c) 2005 The Electrochemical Society. All rights reserved.